"We are and remain confident that Michael will pull through and will wake up," his family said in a statement, issued by spokeswoman Sabine Kehm.

"There sometimes are small, encouraging signs, but we also know that this is the time to be very patient."

Schumacher remains in hospital in Grenoble, and his family said on January 30 that drugs used to keep him in a coma were being reduced with a view to bringing him back to consciousness.

"Michael has suffered severe injuries. It is very hard to comprehend for all of us that Michael, who had overcome a lot of precarious situations in the past, has been hurt so terribly in such a banal situation," the statement said.

Schumacher survived a motorbike accident in Spain in 2009, during which he suffered head and neck injuries but was released from hospital after just five hours.

And after years of racing in the risky world of Formula One, he retired but kept pursuing other high-thrill hobbies as the holder of a pilot's licence, an accomplished motorbike rider, parachutist, skier and mountain climber.

Ms Kehm once again asked that the privacy of Schumacher's wife Corinna and their two children be respected, while thanking well-wishers for their support.

"I would like to remind all of us that Michael has always actively kept his family out of the public eye and consequently protected their private lives," she said in the statement.

Little has filtered out about Schumacher's current condition, but last month his friend and former team-mate Felipe Massa was quoted as saying that Schumacher seemed to respond to him during a recent visit.

"He is sleeping, he looks normal and he showed a few responses with his mouth," Massa told German tabloid Bild.